my question is: while putting hyperlinks to external topics ,
the options where you choose to open the links in 'New window' or
'pop up window' becomes inactive. deos this mean I cannot open
external links in new windows or pop ups????

It works in WebHelp, but a quick test of HTML Help just
proved me wrong in assuming the same functionality in both outputs.

I
did test adding "target=_blank" to the link in TrueCode, and
that worked (although that creates a separate browser window, which
isn't what you want). Maybe someone else in the forum has
experience with secondary windows (I haven't in years) and can
chime in (something like "target=specialpopupwindow" or whatever).